knife-edge

Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

n. A sharp cutting edge.

n. A sharp, narrow edge or border: "saying lines that teeter on the knife-edge between literature and lunacy” ( Vincent Canby).

n. A wedge of metal used as a low-friction fulcrum for a balancing beam or lever.

from Wiktionary, Creative Commons Attribution/Share-Alike License

n. A piece of steel sharpened to an acute edge or angle, and resting on a smooth surface, serving as the axis of motion of a pendulum, scale beam, or other piece required to oscillate with the least possible friction.

n. A precarious balance that could be upset by a very small force in either direction.

n. Used other than as an idiom: the edge of a knife.

from the GNU version of the Collaborative International Dictionary of English

n. A piece of steel sharpened to an acute edge or angle, and resting on a smooth surface, serving as the axis of motion of a pendulum, scale beam, or other piece required to oscillate with the least possible friction.

from The Century Dictionary and Cyclopedia

n. The wedge-like piece of steel which serves as the axis on the fine edge of which a scale-beam, a pendulum, or any thing required to oscillate with the least possible friction rests and turns. See balance.

Etymologies

Sorry, no etymologies found.

Examples

And after Davies gives a number of remarkable facts about the incredible fine-tuning of the universe, he adds, “The cliché that “life is balanced on a knife-edge” is a staggering understatement in this case: no knife in the universe could have an edge that fine.”

But Fox News had to suddenly cut away from Palin to hear third place loser Jon Huntsman flap his jaws.9.40pm: Tim Carney of the Washington Examiner uses an apt sports metaphor:9.39pm: Back to the knife-edge battle between Newt Gingrich and Rick Santorum: with 46% of precincts in, Gingrich is a mere 74 votes ahead of Santorum.